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runtime: introduce unsafe.New and unsafe.NewArray

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to provide functionality previously hacked in to
    reflect and gob.

R=r
https://golang.org/cl/165076
This commit is contained in:
Russ Cox 2009-12-07 15:51:58 -08:00
parent a4a8224152
commit 33649bd278
7 changed files with 78 additions and 37 deletions
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26
src/pkg/gob/decode.go
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@ -13,6 +13,7 @@ import (
"math";
"os";
"reflect";
"runtime";
"unsafe";
)
@ -361,10 +362,8 @@ func decodeStruct(engine *decEngine, rtyp *reflect.StructType, b *bytes.Buffer,
up = decIndirect(up, indir)
}
if *(*unsafe.Pointer)(up) == nil {
// Allocate object by making a slice of bytes and recording the
// address of the beginning of the array. TODO(rsc).
b := make([]byte, rtyp.Size());
*(*unsafe.Pointer)(up) = unsafe.Pointer(&b[0]);
// Allocate object.
*(*unsafe.Pointer)(up) = unsafe.New((*runtime.StructType)(unsafe.Pointer(rtyp)))
}
p = *(*uintptr)(up);
}
@ -437,10 +436,8 @@ func decodeArray(atyp *reflect.ArrayType, state *decodeState, p uintptr, elemOp
if indir > 0 {
up := unsafe.Pointer(p);
if *(*unsafe.Pointer)(up) == nil {
// Allocate the array by making a slice of bytes of the correct size
// and taking the address of the beginning of the array. TODO(rsc).
b := make([]byte, atyp.Size());
*(**byte)(up) = &b[0];
// Allocate object.
*(*unsafe.Pointer)(up) = unsafe.New(atyp)
}
p = *(*uintptr)(up);
}
@ -466,23 +463,22 @@ func ignoreArray(state *decodeState, elemOp decOp, length int) os.Error {
}
func decodeSlice(atyp *reflect.SliceType, state *decodeState, p uintptr, elemOp decOp, elemWid uintptr, indir, elemIndir int, ovfl os.ErrorString) os.Error {
length := uintptr(decodeUint(state));
n := int(uintptr(decodeUint(state)));
if indir > 0 {
up := unsafe.Pointer(p);
if *(*unsafe.Pointer)(up) == nil {
// Allocate the slice header.
*(*unsafe.Pointer)(up) = unsafe.Pointer(new(reflect.SliceHeader))
*(*unsafe.Pointer)(up) = unsafe.Pointer(new([]unsafe.Pointer))
}
p = *(*uintptr)(up);
}
// Allocate storage for the slice elements, that is, the underlying array.
data := make([]byte, length*atyp.Elem().Size());
// Always write a header at p.
hdrp := (*reflect.SliceHeader)(unsafe.Pointer(p));
hdrp.Data = uintptr(unsafe.Pointer(&data[0]));
hdrp.Len = int(length);
hdrp.Cap = int(length);
return decodeArrayHelper(state, hdrp.Data, elemOp, elemWid, int(length), elemIndir, ovfl);
hdrp.Data = uintptr(unsafe.NewArray(atyp.Elem(), n));
hdrp.Len = n;
hdrp.Cap = n;
return decodeArrayHelper(state, hdrp.Data, elemOp, elemWid, n, elemIndir, ovfl);
}
func ignoreSlice(state *decodeState, elemOp decOp) os.Error {